TECHNICAL FIELD
[0001] The present invention relates to a coating composition for forming antireflective
film, and an article on which an antireflective film is formed.
BACKGROUND ART
[0002] As antireflective films, the following films are known.
- (1) An antireflective film containing hollow fine particles and a binder (Patent Document
1).
- (2) An antireflective film containing fibrous solid fine particles, spherical solid
fine particles and a binder (Patent Document 2).
- (3) An antireflective film containing hollow fine particles, solid fine particles
larger than the hollow fine particles, and a binder (Patent Document 3).
[0003] In the antireflective film of (1), since strength of hollow fine particles is insufficient,
it is necessary to increase the amount of the binder to obtain sufficient film strength.
However, if the binder is increased, voids in the film decreases, the refractive index
of the film increases, and the antireflective effect decreases.
[0004] In the antireflective film of (2), since it does not contain hollow fine particles,
film strength is sufficient. However, since there is little void in the film, the
refractive index of the film is high and antireflective film effect is insufficient.
[0005] In the antireflective film of (3), since it contains solid fine particles larger
than the hollow fine particles, its film strength is improved. However, by coating
solid fine particles larger than the hollow fine particles, voids in the film are
decreased, the refractive index of the film is increased, and the antireflective effect
becomes insufficient.
Patent Document 1: JP-A-2001-233611
Patent Document 2: JP-A-2005-010470
Patent Document 3: JP-A-2006-117924
DISCLOSURE OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0006] The present invention provides a coating composition for forming antireflective film,
which can form an antireflective film having high antireflective effect and high film
strength, and an article having high antireflective effect for long period of time.
MEANS OF SOLVING THE PROBLEMS
[0007] The present invention has the following gists.
- (1) A coating composition for forming antireflective film containing a dispersion
medium, fibrous solid fine particles, hollow fine particles and a binder, wherein
an average agglomerated particle size of the fibrous solid fine particles measured
by a dynamic light-scattering method is larger than an average agglomerated particle
size of the hollow fine particles measured by a dynamic light-scattering method.
- (2) The coating composition for forming antireflective film according to the above
(1)., wherein any one of the fibrous solid fine particles, the hollow fine particles
and the binder contains SiO2.
- (3) The coating composition for forming antireflective film according to the above
(1), wherein the fibrous solid fine particles and the hollow fine particles contain
SiO2.
- (4) The coating composition for forming antireflective film according to any one of
the above (1) to (3), wherein the hollow fine particles are fibrous hollow fine particles.
- (5) The coating composition for forming antireflective film according to any one of
the above (1) to (4), wherein an aspect ratio of the fibrous solid fine particles
or the hollow fine particles is from 2 to 10.
- (6) The coating composition for forming antireflective film according to any one of
the above (1) to (4), wherein aspect ratios of the fibrous solid fine particles and
the hollow fine particles are each from 2 to 10.
- (7) The coating composition for forming antireflective film according to any one of
the above (1) to (6), wherein a mass ratio (fibrous solid fine particles/hollow fine
particles) between the fibrous solid fine particles and the hollow fine particles
is from 0.1 to 1.5.
- (8) The coating composition for forming antireflective film according to any one of
the above (1) to (6), wherein a mass ratio (fibrous solid fine particles/hollow fine
particles) between the fibrous solid fine particles and the hollow fine particles
is from 0.25 to 1.5.
- (9) An article on which an antireflective film produced from the coating composition
for forming antireflective film as defined in any one of the above (1) to (8) is formed.
- (10) The article according to the above (9), wherein the ratio (average agglomerated
particle size of fibrous solid fine particles/film thickness of antireflective film)
between the average agglomerated particle size of the fibrous solid fine particles
measured by a dynamic light-scattering method and the film thickness of the antireflective
film, is from 0.5 to 1.0.
- (11) The article according to the above (9) or (10), wherein the film thickness of
the antireflective film is from 50 to 300 nm.
EFFECTS OF THE INVENTION
[0008] According to the coating composition for forming antireflective film of the present
invention, it is possible to form an antireflective film having high antireflective
effect and high film strength.
[0009] The article of the present invention can maintain high antireflective effect for
long period of time.
BEST MODE FOR CARRYING OUT THE INVENTION
FIBROUS SOLID FINE PARTICLES
[0010] "Fibrous" in the fibrous solid fine particles means that the length in the extension
direction is larger than the length in a direction perpendicular to the extension
direction. The fibrous solid fine particles may be primary particles or secondary
particles each consisting of a plurality of agglomerated solid fine particles. Namely,
the fibrous solid fine particles include both of solid fine particles that are primary
particles each having a length in the extension direction longer than the length in
a direction perpendicular to the extension direction, and solid fine particles that
are secondary particles each having a length in the extension direction longer than
the length in a direction perpendicular to the extension direction (each consisting
of primary particles of any shape). The fibrous solid fine particles are preferably
ones of needle shape or rod shape, the secondary particles each consisting of a plurality
of connected solid fine particles, are preferably ones of chain shape or pearl necklace
shape. The shape of the fibrous solid fine particles may be a linearly extending shape
or a two-dimensionally or three-dimensionally curved shape etc., and for the reason
that voids are easily formed between adjacent fibrous solid fine particles, it is
preferably two-dimensionally or three-dimensionally curved shape, more preferably
three-dimensionally curved shape. The length of particles in the extension direction
are different from one another, and the length is distributed in a certain range.
The average length of particles in the extension direction means the average value
of the distribution. The average length in the direction perpendicular to the extension
direction is defined in the same manner.
[0011] The material of the fibrous solid fine particles may, for example, be an inorganic
material such as SiO
2, Al
2O
3, SnO
2 (ATO, FTO), TiO
2, ZrO
2, ZnO (AZO, GZO), Fe
2O
3, CeO
2, Sb
2O
3, Sb
2O
5, In
2O
3 (ITO) or carbon; or an organic material such as an acrylic resin, a styrene resin,
an urethane acrylate resin, an epoxy acrylate resin, a polyester acrylate, a polyether
acrylate, an epoxy resin or a silicone resin; and for the reasons of relatively low
refractive index, excellent chemical stability and excellent adhesiveness to glass,
it is preferably a material containing SiO
2, and more preferably a material consisting essentially of SiO
2.
[0012] The average agglomerated particle size of the fibrous solid fine particles is preferably
from 20 to 200 nm, more preferably from 50 to 100 nm. When the average agglomerated
particle size of the fibrous solid fine particles is at least 20 nm, sufficient voids
are formed between adjacent fibrous solid fine particles, and accordingly, the refractive
index of the antireflective film decreases and antireflective effect increases. When
the average agglomerated particle size of the fibrous solid fine particles is at most
200 nm, scattering of light is suppressed and an antireflective film having high transparency
can be obtained.
[0013] The average agglomerated particle size of the fibrous solid fine particles is the
average agglomerated particle size of the fibrous solid fine particles in a dispersion
medium, and it is measured by a dynamic light-scattering method.
[0014] The refractive index of the fibrous solid fine particles is preferably from 1.3 to
3.0, more preferably from 1.3 to 2.0. When the refractive index of the fibrous solid
fine particles is at least 1.3, an antireflective film having a refractive index of
at least 1.2 is easily obtainable, and an antireflective film excellent in antireflective
performance when it is provided on a glass substrate, is obtainable. When the refractive
index of the fibrous solid fine particles is at most 3.0, an antireflective film having
a refractive index of at most 1.4 is easily obtainable, and an antireflective film
excellent in antireflective performance when it is provided on a glass substrate is
obtained.
[0015] The refractive index of the fibrous solid fine particles is a refractive index at
550 nm, and it is determined by measuring the refractive index of the fine particles
in a state that they are dispersed in a dispersion medium or in a state that they
are formed into a thin coating film together with matrix, by using a refractive index
meter, and converting the measured value by considering volume ratio.
[0016] The aspect ratio of the fibrous solid fine particles is preferably from 2 to 10,
more preferably from 5 to 10. When the aspect ratio of the fibrous solid fine particles
is at least 2, sufficient voids are formed between adjacent fibrous solid fine particles,
and accordingly, the refractive index of the antireflective film decreases, and the
antireflective effect increases. When the aspect ratio of the fibrous solid fine particles
is at most 10, film-forming property becomes excellent and an antireflective film
excellent in external appearance can be obtained.
[0017] The aspect ratio of the fibrous solid fine particles is a value calculated by dividing
the length of the fine particles in the extension direction by the length in a direction
perpendicular to the extension direction, and the length in the extension direction
and the length in a direction perpendicular to the extension direction are observed
by e.g. an electron microscope. Here, with respect to simply dispersed fibrous solid
fine particles without having secondary agglomeration, the aspect ratios of the fibrous
solid fine particles, that are primary particles, are observed. With respect to fibrous
solid fine particles undergoing secondary agglomeration to form a secondary particle
having a length in the extension direction longer than the length in a direction perpendicular
to the extension direction, the aspect ratio of the secondary particle is observed.
[0018] The fibrous solid fine particles are available as a commercial product. The commercial
product of fibrous solid fine particles may, for example, be "IPA-ST-UP" manufactured
by Nissan Chemical Industries, Ltd.
[0019] Further, the fibrous solid fine particles can be produced by a known production method.
The method for producing fibrous solid fine particles may, for example, be a method
described in the example of
JP-A-1-317115. Specifically, by adding a binder component to a dispersion of solid fine particles
and heating them under the presence of multivalent metal ions, fibrous solid fine
particles are obtained.
HOLLOW FINE PARTICLES
[0020] The hollow fine particles are particles each having a void inside of an outer shell.
The hollow fine particles may, for example, be spherical hollow fine particles or
fibrous hollow fine particles each having a length in the extension direction longer
than the length in a direction perpendicular to the extension direction, and the hollow
fine particles are preferably fibrous hollow fine particles for the reason that a
void is easily formed between adjacent particles. In the same manner as the case of
fibrous solid fine particles, the fibrous hollow fine particles may be primary particles
or secondary particles each consisting of a plurality of agglomerated hollow fine
particles.
[0021] The material of the hollow fine particles may, for example, be an inorganic material
such as SiO
2, Al
2O
3, SnO
2 (ATO, FTO), TiO
2, ZrO
2, ZnO (AZO, GZO), Fe
2O
3, CeO
2, Sb
2O
3, Sb
2O
5, In
2O
3 (ITO) or carbon; or an organic material such as an acrylic resin, a styrene resin,
an urethane acrylate resin, an epoxy acrylate resin, a polyester acrylate, a polyether
acrylate, an epoxy resin or a silicone resin; and for the reasons of relatively low
refractive index, excellent chemical stability and excellent adhesiveness to glass,
it is preferably a material containing SiO
2, and more preferably a material consisting essentially of SiO
2.
[0022] In the present invention, it is particularly preferred that both of the fibrous solid
fine particles and the hollow fine particles contain SiO
2.
[0023] The average agglomerated particle size of the hollow fine particles is preferably
from 5 to 300 nm, more preferably from 10 to 100 nm. When the average agglomerated
particle size of the hollow fine particles is at least 5 nm, sufficient voids are
formed between adjacent hollow fine particles, and accordingly, the refractive index
of the antireflective film decreases and antireflective effect increases. When the
average agglomerated particle size of hollow fine particles is at most 300 nm, scattering
of light can be suppressed, and an antireflective film having high transparency can
be obtained.
[0024] The average agglomerated particle size of the hollow fine particles is the average
agglomerated particle size of the hollow fine particles in a dispersion medium, and
that is measured by a dynamic light-scattering method. Accordingly, in a case of spherical
hollow fine particles of single dispersion having no secondary agglomeration, the
average agglomerated particle size substantially agrees with the average primary particle
size.
[0025] The thickness of an outer shell of a hollow fine particles is preferably from 1 to
50 nm, and it is preferably from 1/20 to 1/3 of the average primary particle size
of the hollow fine particles. When the thickness of the outer shells of the hollow
fine particles is within this range, an antireflective film having sufficient strength
and excellent antireflective performance can be obtained.
[0026] The thickness of outer shells and the average primary particle size of the hollow
fine particles are values obtained by observing hollow fine particles by a transmission
type electron microscope, selecting 100 particles randomly, measuring the thickness
of the outer shell and the particle size of each of the hollow fine particles, and
averaging the thicknesses of the outer shells of the 100 hollow fine particles and
averaging particle sizes of these particles.
[0027] The refractive index of the hollow fine particles is preferably from 1.1 to 1.4,
more preferably from 1.2 to 1.35. When the refractive index of the hollow fine particles
is at least 1.1, it is easy to obtain an antireflective film having a refractive index
of at least 1.2, and an antireflective film excellent in antireflective performance
when it is provided on a glass substrate can be obtained. When the refractive index
of the hollow fine particles is at most 1.4, it is easy to obtain an antireflective
film having a refractive index of at most 1.4, and an antireflective film excellent
in antireflective performance when it is provided on a glass substrate can be obtained.
[0028] The refractive index of the hollow fine particles is a refractive index at 550 nm,
and is determined by measuring the refractive index of the particles in a state that
they are dispersed in a dispersion medium or in a state that they are formed into
a coating film together with a matrix, by a refractive index meter, and converting
the measured value by considering volume ratio.
[0029] The hollow fine particles may be, besides the above spherical hollow fine particles
or fibrous hollow fine particles, fine particles of tube-shape or sheet-shape may
also be employed as primary particles. Further, for the reason that a void is easily
formed between adjacent fine particles and an antireflective film excellent in antireflective
performance can be easily obtained, fibrous hollow fine particles are preferred. The
aspect ratio of the fibrous hollow fine particles is preferably from 2 to 10, more
preferably from 5 to 10. When the aspect ratio of the fibrous hollow fine particles
is at least 2, sufficient voids are formed between adjacent fine particles, and accordingly,
the refractive index of the antireflective film decreases and antireflective effect
increases. When the aspect ratio of the fibrous hollow fine particles is at most 10,
film-forming property becomes excellent and an antireflective film excellent in external
appearance can be obtained.
[0030] The aspect ratio of the fibrous hollow fine particles is a value obtained by dividing
the length of a fine particle in the extension direction by the direction in a direction
perpendicular to the extension direction, and the length in the extension direction
and the length in a direction perpendicular to the extension direction are observed
by e.g. an electron microscope. Here, with respect to fibrous hollow fine particles
of single dispersion undergoing no secondary agglomeration, the aspect ratio of the
fibrous hollow fine particles that are primary particles is observed. With respect
to fibrous hollow fine particles agglomerated to form a secondary particle having
a length in the extension direction longer than a length in a direction perpendicular
to the extension direction, the aspect ratio of the secondary particle is observed.
[0031] In the present invention, it is preferred that both of the aspect ratio of the fibrous
solid fine particles and the aspect ratio of the hollow fine particles are from 2
to 10, more preferably from 5 to 10.
[0032] The spherical hollow fine particles are produced, for example, by removing a core
of each core-shell particle.
[0033] Specifically, when the outer shell (shell) is made of SiO
2, the particles are produced by the following steps.
- (a) A step of hydrolyzing a SiO2 precursor material in a dispersion medium under the presence of core fine particles,
to precipitate SiO2 on each core fine particle surface to obtain core-shell particles.
- (b) A step of dissolving or decomposing the core of each core-shell particle.
(a) STEP:
[0034] As the core particles, thermally decomposable organic fine particles (surfactant
micells, water-soluble organic polymers, styrene resins, acrylic resins, etc.), acid-soluble
inorganic fine particles (ZnO, NaAlO
2, CaCO
3, basic ZnCO
3, etc.) or opto-soluble inorganic fine particles (ZnS, CdS, ZnO, etc.).
[0035] The SiO
2 precursor material may, for example, be silicic acid, a silicate or a silicic alkoxide.
The dispersion medium may, for example, be water, an alcohol (methanol, ethanol, isopropanol,
etc.), a ketone (acetone, methyl ethyl ketone, etc.), an ether (tetrahydrofuran, 1,4-dioxane,
etc.), an ester (ethyl acetate, methyl acetate, etc.), a glycol ether (ethylene glycol
monoalkyl ether, etc.), a nitrogen-containing compound (N,N-dimethylacetamide, N,N-dimethylformamide,
etc.) or a sulfur-containing compound (dimethylsul-foxide, etc.).
[0036] The dispersion medium contains from 5 to 100 mass% of water based on 100 mass% of
dispersion medium since water is required for hydrolyzing the SiO
2 precursor material.
[0037] The pH of the dispersion medium is preferably at least 7, more preferably at least
8, particularly preferably from 9 to 10 for the reason that the SiO
2 precursor material is easily polymerized three-dimensionally to form a shell. In
a case of employing acid-soluble inorganic fine particles as core fine particles,
the pH is preferably at least 8 at which the fine particles are not soluble.
(b) STEP:
[0038] When the core fine particles are acid-soluble inorganic fine particles, the core
fine particles can be dissolved by adding an acid to thereby remove these core fine
particles.
[0039] The acid may, for example, be an inorganic acid (hydrochloric acid, sulfuric acid,
nitric acid, etc.), an organic acid (formic acid, acetic acid, etc.) or an acidic-cation-exchanged
resin.
[0040] The fibrous hollow fine particles that are primary particles and are elongated hollow
fine particles, can be produced by using fibrous solid fine particles as cores, forming
shells thereon, and thereafter, removing the cores. The fibrous hollow fine particles
each consisting of a plurality of connecetd hollow fine particles, can be produced
in the same manner as the production method for the fibrous solid fine particles that
are secondary particles being agglomerations, except that hollow fine particles are
used instead of solid fine particles.
[0041] The hollow fine particles may be subjected to hydrothermal treatment for improving
strength.
BINDER
[0042] The binder may be a hydrolyzable silane (tetramethoxysilane, tetraethoxysilane, etc.),
an oligomer silicate obtainable by hydrolyzing a hydrolyzable silane, a silicon compound
(a silicate, a trimethyl silanol, etc.) having a silanol group, an active silica (a
water glass, an ortho sodium silicate, etc.), or an organic polymer (a polyethylene
glycol, a polyacrylamide derivative, a polyvinyl alcohol, etc.). The binder is particularly
preferably an oligomer silicate containing SiO
2.
[0043] In the present invention, it is particularly preferred that each of the fibrous solid
fine particles, hollow fine particles and the binder contains SiO
2.
DISPERSION MEDIUM
[0044] The dispersion medium may, for example, be water, an alcohol (methanol, ethanol,
isopropanol, etc.), a ketone (acetone, methyl ethyl ketone, etc.), an ether (tetrahydrofuran,
1,4-dioxane, etc.), an ester (ethyl acetate, methyl acetate, etc.), a glycol ether
(ethylene glycol monoalkyl ether, etc.), a nitrogen-containing compound (N,N-dimethylacetamide,
N,N-dimethylformamide, etc.) or a sulfur-containing compound (dimethylsulfoxide, etc.).
COATING SOLUTION FOR FORMING ANTIREFLECTIVE FILM
[0045] The coating solution for forming antireflective film of the present invention contains
a dispersion medium, fibrous solid fine particles, hollow fine particles and a binder.
[0046] The average agglomerated particle size of the fibrous solid fine particles measured
by the dynamic light-scattering method is at least the average agglomerated particle
size of the hollow fine particles measured by the dynamic light-scattering method.
When the average agglomerated particle size of the fibrous solid fine particles is
at least the average agglomerated particle size of the hollow fine particles, the
fibrous solid fine particles having high strength mainly receives external pressure,
whereby the hollow fine particles having low strength become less likely be squashed
and the film strength of the antireflective film increases. The ratio between the
average agglomerated particle size of the fibrous solid fine particles and the average
agglomerated particle size of the hollow fine particles (average agglomerated particle
size of fibrous solid fine particles/average agglomerated particle size of hollow
fine particles) is necessarily at least 1.0, preferably from 1.0 to 5.0, more preferably
from 1.2 to 4.0.
[0047] The mass ratio between the fibrous solid fine particles and the hollow fine particles
(fibrous solid fine particles/hollow fine particles) is preferably from 0.1 to 1.5,
more preferably from 0.25 to 1.5. When the ratio of the fibrous solid fine particles/hollow
fine particles (mass ratio) is at least 0.1, an antireflective film having sufficient
film strength can be formed. When the ratio of fibrous solid fine particles/hollow
fine particles (mass ratio) is at most 1.5, it is possible to maintain low refractive
index of the antireflective film and to form an antireflective film having high antireflective
effect.
[0048] The mass ratio between the binder and all particles (binder/(fibrous solid fine particles+hollow
fine particles)) is preferably from 0.1 to 2.0, more preferably from 0.2 to 1.0. When
the ratio of binder/(fibrous solid fine particles+hollow fine particles) (mass ratio)
is at least 0.1, an antireflective film having sufficient film strength can be formed.
When the ratio of binder/(fibrous solid fine particles+hollow fine particles) (mass
ratio) is at most 2.0, it is possible to maintain low refractive index of antireflective
film and to form an antireflective film having high antireflective effect.
[0049] The solid content concentration in the coating composition for forming antireflective
film of the present invention is preferably from 0.1 to 20.0 mass%.
[0050] The coating composition for forming antireflective film of the present invention
may contain solid fine particles (spherical solid fine particles, sheet-shaped solid
fine particles, etc.) other than the fibrous solid fine particles to the extent not
impairing the effect of the present invention.
[0051] The coating composition for forming antireflective film of the present invention
may contain an alkali earth metal salt such as chloride, nitrate, sulfate, formate
or acetate of magnesium, calcium, strontium or barium; a curing catalyst such as an
inorganic acid, an organic acid, a base, a metal chelate compound, a quaternary ammonium
salt or an organic tin; or a known additive such as inorganic fine particles, an organic
pigment, a die or an organic resin each showing UV-shielding property, infrared-shielding
property or conductivity.
[0052] The coating composition for forming antireflective film of the present invention
described above contains fibrous solid fine particles and hollow fine particles, wherein
the average agglomerated particle size of the fibrous solid fine particles measured
by the dynamic light-scattering method is larger than the average agglomerated particle
size of the hollow fine particles measured by the dynamic light-scattering method,
whereby the hollow fine particles are not likely to be squashed and the film strength
of the antireflective film becomes high. Further, since fibrous solid fine particles
are employed as solid fine particles, voids are formed between adjacent fibrous solid
fine particles, and the refractive index of the antireflective film becomes low. Accordingly,
it is possible to increase antireflective effect of the antireflective film while
high strength of the antireflective film is maintained.
ARTICLE ON WHICH ANTIREFLECTIVE FILM IS FORMED
[0053] The article of the present invention is an article on which an antireflective film
formed from the coating solution for forming antireflective film of the present invention
is formed.
[0054] The film thickness of the antireflective film is preferably from 50 to 300 nm, more
preferably from 80 to 200 nm. When the film thickness of the antireflective film is
at least 50 nm, interference of light occurs and antireflective performance is exhibited.
When the film thickness of the antireflective film is at most 300 nm, it is possible
to form the film without having cracks.
[0055] The film thickness of the antireflective film can be determined by measuring a step
between a coated area and non-coated area by a step height meter.
[0056] The ratio between the average agglomerated particle size of the fibrous solid fine
particles measured by a dynamic light-scattering method and the film thickness of
the antireflective film (average agglomerated particle size of fibrous solid fine
particles/film thickness of antireflective film) is preferably from 0.5 to 1.0, more
preferably from 0.7 to 0.9. When the ratio of average agglomerated particle size of
fibrous solid fine particles/film thickness of antireflective film is at least 0.5,
the fibrous solid fine particles having high strength mainly receives external pressure,
whereby hollow fine particles having low strength becomes unlikely be squashed and
the film strength of the antireflective film increases. When the ratio of average
agglomerated particle size of fibrous solid fine particles/film thickness of antireflective
film is at most 1.0, the fibrous solid fine particles do not extrude from the surface
of the antireflective film, whereby the fibrous solid fine particles become unlikely
come off from the antireflective film.
[0057] The refractive index of the antireflective film is preferably from 1.2 to 1.4, more
preferably from 1.23 to 1.35. When the refractive index of the antireflective film
is at least 1.2, light reflected at the upper face of the film and light reflected
at the lower face of the film interfere and cancel each other, whereby an antireflective
film excellent in antireflective performance can be obtained. When the refractive
index of the antireflective film is at most 1.4, light reflected at the upper face
of the film and light reflected at the lower face of the film interfere and cancel
each other, whereby an antireflective film excellent in antireflective performance
can be obtained when the film is provided on a glass substrate.
[0058] The refractive index of the antireflective film is an antireflective film at 550
nm, and it is measured by a refractive index meter.
[0059] The antireflective film can be formed by coating a substrate surface with the coating
composition for forming antireflective film of the present invention, and drying the
coated film.
[0060] The material of the substrate may, for example, be a glass, a metal, an organic polymer
or silicon, and the substrate may have another coated film in advance. The organic
polymer may, for example, be polyethylene terephthalate, polycarbonate or polymethyl
methacrylate.
[0061] The shape of the substrate may, for example, be a plate or a film.
[0062] The coating method may, for example, be bar coating, die coating, gravure coating,
roll coating, flow coating, spray coating, online spray coating or dip coating. The
online spray coating is a method of performing a spray coating of a substrate in a
molding line of the substrate, which is useful since a step of reheating the substrate
can be omitted and a product can be produced at low cost.
[0063] The article of the present invention described above has an antireflective film having
high antireflective performance and high film strength, whereby high antireflective
effect can be maintained for a long period of time.
EXAMPLES
[0064] From now, the present invention will be described in further detail with reference
to Examples, but the present invention is not limited to these Examples.
[0065] Examples 1 to 9 are Examples of the present invention, and Examples 10 to 15 are
Comparative Examples.
OUTER SHELL THICKNESS AND AVERAGE PRIMARY PARTICLE SIZE OF HOLLOW FINE PARTICLES
[0066] The hollow fine particles are observed by a transmission type electron microscope
(H-9000, manufactured by Hitachi, Ltd.), 100 particles (primary particles) are randomly
selected, outer shell thickness and particle size of these hollow fine particles were
measured, and the outer shell thicknesses and the particle sizes of the 100 hollow
fine particles are each averaged, to determine the outer shell thickness and the average
primary particle size of the hollow fine particles.
AVERAGE AGGLOMERATED PARTICLE SIZE OF FINE PARTICLES
[0067] The average agglomerated particle size of the fine particles were measured by using
a dynamic light-scattering particle analyzer (Microtrac UPA, manufactured by Nikkiso
Co., Ltd.). In a case of single dispersion having no secondary agglomeration, the
average primary particle size and the average agglomerated particle size of spherical
fine particles substantially agree with each other.
ASPECT RATIO OF FINE PARTICLES
[0068] The aspect ratio of primary particles or secondary particles were determined by observing
fine particles by a transmission type electron microscope (H-9000, manufactured by
Hitachi, Ltd.), randomly selecting 100 particles (primary particles or secondary particles),
measuring the length in the extension direction and the length in a direction perpendicular
to the extension direction of each particle, and averaging values obtained by dividing
the length in the extension direction by the length in a direction perpendicular to
the extension direction.
EXTERNAL APPEARANCE
[0069] The antireflective film was visually observed, and evaluated under the following
criteria.
○: There is no coating unevenness and external appearance is good.
×: There is coating unevenness and the film is not practically usable.
HAZE VALUE
[0070] According to JIS K-7105 (year 1981), the haze value of the antireflective film on
a substrate was measured by a haze computer (HGM-3DP, manufactured by Suga Test Instruments
Co., Ltd.).
MINIMUM REFLECTIVITY
[0071] The reflectivity of the antireflective film on a substrate within a range of from
380 to 1,200 nm was measured by a spectrophotometer (model U-4100, manufactured by
Hitachi, Ltd.), and the minimum value of reflectivity was determined. A surface of
the antireflective film was abraded by 1,000 shuttles with a felt with 100 g load,
and thereafter, the reflectivity was measured in the same manner to determine the
minimum value of reflectivity.
[0072] The difference (Δ reflectivity) between the minimum reflectivity after abrasion and
the minimum reflectivity before abrasion was determined.
PRODUCTION EXAMPLE 1
PRODUCTION OF SPHERICAL HOLLOW FINE PARTICLES (1):
[0073] In a container of 200 mL made of glass, 60 g of ethanol, 30 g of water-dispersion
sol of ZnO fine particles (average primary particle size: 20 nm, average agglomerated
particle size: 40 nm, solid content converted concentration: 20 mass%) and 10 g of
tetraethoxysilane (SiO
2 solid content concentration: 29 mass%) were put, an ammonium aqueous solution was
added to form a mixture of pH 10, it was stirred at 20°C for 6 hours to form 100 g
of dispersion of core-shell particles (solid content concentration: 6 mass%).
[0074] To the 100 g of dispersion of core-shell particles, 100 g of strong-acid-cation-exchanged
resin (total exchange capacity: at least 2.0 meq/mL), they were stirred for 1 hour
to form a mixture of pH 4, it was filtered to remove the strong-acid-cation-exchanged
resin to obtain a dispersion of spherical hollow fine particles (1) made of SiO
2. The dispersion was condensed by ultrafiltration so that its solid content concentration
became 20 mass%. The spherical hollow fine particles (1) underwent.secondary agglomeration.
The outer shell thickness of the spherical hollow fine particles (1) was 5 nm, and
it was 1/6 of the average primary particle size. The average agglomerated particle
size of the spherical hollow fine particles (1) was 40 nm. The aspect ratio of the
spherical hollow fine particles (1) was 1.0.
PRODUCTION EXAMPLE 2
PRODUCTION OF SPHERICAL HOLLOW FINE PARTICLES (2):
[0075] A dispersion (solid content concentration: 20 mass%) of the spherical hollow fine
particles (2) made of SiO
2 was obtained in the same manner as Production Example 1 except that the water-dispersion
sol of ZnO fine particles (average primary particle size: 20 nm, average agglomerated
particle size: 60 nm, solid content converted concentration: 20 mass%) was used instead
of the above water-dispersion sol of ZnO fine particles. The outer shell thickness
of the spherical hollow fine particles (2) was 5 nm, and it was 1/6 of the average
primary particle size. The average agglomerated particle size of the spherical hollow
fine particles (2) was 60 nm. The aspect ratio of the spherical hollow fine particles
(2) was 1.0.
PRODUCTION EXAMPLE 3
PRODUCTION OF FIBROUS HOLLOW FINE PARTICLES (1):
[0076] In a container made of glass, 2,000 g of dispersion (solid content concentration:
3 mass%) of the spherical hollow fine particles (1) were put, and as they were stirred,
8.0 g of 10 mass% of calcium chloride aqueous solution and 12.0 g of 10 mass% potassium
hydroxide aqueous solution were added. A mixed solution thus produced was put in an
autoclave container of 2.5 L made of stainless steel, the solution was heated at 130°C
for 24 hours to obtain a dispersion of fibrous hollow fine particles (1). The dispersion
was concentrated by ultrafiltration so that its solid content concentration became
20 mass%. The fibrous hollow fine particles (1) underwent secondary agglomeration.
The average agglomerated particle size of the fibrous hollow fine particles (1) was
70 nm. The aspect ratio of the fibrous hollow fine particles (1) was 5.0.
PRODUCTION EXAMPLE 4
PRODUCTION OF FIBROUS HOLLOW FINE PARTICLES (2):
[0077] A dispersion (solid content concentration: 20 mass%) of fibrous hollow fine particles
(2) was obtained in the same manner as Production Example 3 except that the heating
time in the autoclave container was changed to 6 hours. The fibrous hollow fine particles
(2) underwent secondary agglomeration. The average agglomerated particle size of the
fibrous hollow fine particles (2) was 50 nm. The aspect ratio of the fibrous hollow
fine particles (2) was 2.0.
PRODUCTION EXAMPLE 5
PRODUCTION OF FIBROUS SOLID FINE PARTICLES (2):
[0078] 2,000 g of colloid aqueous solution (SiO
2 solid content concentration: 3.56 mass%, pH: 2.81) of activated silicic acid was
put, and while it was stirred, 8.0 g of 10 mass% calcium chloride aqueous solution
and 12.0 g of 10 mass% sodium hydroxide aqueous solution were added. A mixed solution
thus produced was put in an autoclave container of 2.5 L made of stainless steel,
and it was heated at 130°C for 24 hours to obtain a dispersion of fibrous solid fine
particles (2). The dispersion was concentrated by ultrafiltration so that its solid
component concentration became 15 mass%. The fibrous solid fine particles (2) underwent
secondary agglomeration. The average agglomerated particle size of the fibrous solid
fine particles (2) was 150 nm. The aspect ratio of the fibrous solid fine particles
(2) was 10.0.
COMMERCIALLY AVAILABLE PARTICLES
[0079] Dispersion (single dispersion without secondary agglomeration) of fibrous solid fine
particles (1): IPA-ST-UP manufactured by Nissan Chemical Industries, Ltd., solid content
concentration: 15 mass%, average agglomerated particle size (average primary particle
size): 90 nm, aspect ratio: 7.0.
[0080] Dispersion (single dispersion without secondary agglomeration) of spherical solid
fine particles (1): IPA-ST manufactured by Nissan Chemical Industries, Ltd., solid
content concentration: 30 mass%, average agglomerated particle size (average primary
particle size): 13 nm, aspect ratio: 1.0.
[0081] Dispersion (single dispersion without secondary agglomeration) of spherical solid
fine particles (2): IPA-ST-ZL manufactured by Nissan Chemical Industries, Ltd., solid
content concentration: 30 mass%, average agglomerated particle size (average primary
particle size): 85 nm, aspect ratio: 1.0.
[0082] Dispersion (single dispersion without secondary agglomeration) of spherical solid
fine particles (3): IPA-ST-L manufactured by Nissan Chemical Industries, Ltd., solid
content concentration: 20 mass%, average agglomerated particle size (average primary
particle size): 45 nm, aspect ratio: 1.0.
PRODUCTION EXAMPLE 6
PRODUCTION OF SILICIC ACID OLIGOMER SOLUTION:
[0083] To an ethanol solution of tetraethoxysilane, a nitric acid solution was added so
as to hydrolyze the tetraethoxysilane to obtain a silicic acid oligomer solution (solid
content concentration: 5 mass%).
EXAMPLE 1
[0084] In a container of 200 mL made of glass, 2 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (1), 2 g of dispersion (solid content
concentration: 15 mass%) of fibrous solid fine particles (1), 90 g of ethanol and
6 g of silicic acid oligomer solution (solid content concentration: 5 mass%) were
put, and the mixture was stirred for 10 minutes,to obtain a coating composition for
forming antireflective film.
[0085] The coating composition was applied to a surface of a glass substrate (100 mm × 100
mm, thickness: 3.5 mm) cleaned with an ethanol, it was subjected to spin coating at
a rotation speed of 200 rpm for 60 seconds to be unified, and dried at 200°C for 30
minutes to form an antireflective film having a film thickness of 100 nm, and it was
subjected to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 2
[0086] In a container of 200 mL made of glass, 4 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (1), 4 g of dispersion (solid content
concentration: 15 mass%) of fibrous solid fine particles (2), 80 g of ethanol and
12 g of silicic acid oligomer solution (solid content concentration: 5 mass%) were
put, and the mixture was stirred for 10 minutes to obtain a coating composition for
forming antireflective film.
[0087] An antireflective film having a film thickness of 150 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 3
[0088] In a container of 200 mL made of glass, 3 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (2), 0.7 g of dispersion (solid content
concentration: 15 mass%) of fibrous solid fine particles (1), 90.3 g of ethanol and
6 g of silicic acid oligomer solution (solid content concentration: 5 mass%) were
put, and the mixture was stirred for 10 minutes to obtain a coating composition for
forming antireflective film.
[0089] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 4
[0090] In a container of 200 mL made of glass, 1.5 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (2), 3 g of dispersion (solid content
concentration: 15 mass%) of fibrous solid fine particles (1), 90.5 g of ethanol and
5 g of silicic acid oligomer solution (solid content concentration: 5 mass%) were
put, and the mixture was stirred for 10 minutes to obtain a coating composition for
forming antireflective film.
[0091] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 5
[0092] In a container of 200 mL made of glass, 2 g of dispersion (solid content concentration:
20 mass%) of fibrous hollow fine particles (1), 2 g of dispersion (solid content concentration:
15 mass%) of fibrous solid fine particles (1), 90 g of ethanol and 6 g of silicic
acid oligomer solution (solid content concentration: 5 mass%) were put, and the mixture
was stirred for 10 minutes to obtain a coating composition for forming antireflective
film.
[0093] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 6
[0094] In a container of 200 mL made of glass, 2 g of dispersion (solid content concentration:
20 mass%) of fibrous hollow fine particles (2), 2 g of dispersion (solid content concentration:
15 mass%) of fibrous solid fine particles (1), 90 g of ethanol and 6 g of silicic
acid oligomer solution (solid content concentration: 5 mass%) were put, and the mixture
was stirred for 10 minutes to obtain a coating composition for forming antireflective
film.
[0095] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 7
[0096] In a container of 200 mL made of glass, 1 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (2), 1 g of dispersion (solid content
concentration: 20 mass%) of fibrous hollow fine particles (1), 2 g of dispersion (solid
content concentration: 15 mass%) of fibrous solid fine particles (1), 90 g of ethanol
and 6 g of silicic acid oligomer solution (solid content concentration: 5 mass%) were
put, and the mixture was stirred for 10 minutes to obtain a coating composition for
forming antireflective film.
[0097] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 8
[0098] In a container of 200 mL made of glass, 2.75 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (1), 1 g of dispersion (solid content
concentration: 15 mass%) of fibrous solid fine particles (1), 90.25 g of ethanol and
6 g of silicic acid oligomer solution (solid content concentration: 5 mass%) were
put, and the mixture was stirred for 10 minutes to obtain a coating composition for
forming antireflective film.
[0099] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 9
[0100] In a container of 200 mL made of glass, 2.85 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (1), 0.87 g of dispersion (solid content
concentration: 15 mass%) of fibrous solid fine particles (1), 90.28 g of ethanol and
6 g of silicic acid oligomer solution (solid content concentration: 5 mass%) were
put, and the mixture was stirred for 10 minutes to obtain a coating composition for
forming antireflective film.
[0101] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 10
[0102] In a container of 200 mL made of glass, 3.5 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (2), 90.5 g of ethanol and 6 g of silicic
acid oligomer solution (solid content concentration: 5 mass%) were put, and the mixture
was stirred for 10 minutes to obtain a coating composition for forming antireflective
film.
[0103] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 11
[0104] In a container of 200 mL made of glass, 2 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (1), 1 g of dispersion (solid content
concentration: 30 mass%) of spherical solid fine particles (1), 91 g of ethanol and
6 g of silicic acid oligomer solution (solid content concentration: 5 mass%) were
put, and the mixture was stirred for 10 minutes to obtain a coating composition for
forming antireflective film.
[0105] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 12
[0106] In a container of 200 mL made of glass, 2 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (2), 1 g of dispersion
[0107] (solid content concentration: 30 mass%) of spherical solid fine particles (2), 91
g of ethanol and 6 g of silicic acid oligomer solution (solid content concentration:
5 mass%) were put, and the mixture was stirred for 10 minutes to obtain a coating
composition for forming antireflective film.
[0108] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 13
[0109] In a container of 200 mL made of glass, 2 g of dispersion (solid content concentration:
20 mass%) of spherical hollow fine particles (1), 1.5 g of dispersion (solid content
concentration: 20 mass%) of fibrous hollow fine particles (1), 90.5 g of ethanol and
6 g of silicic acid oligomer solution (solid content concentration: 5 mass%) were
put, and the mixture was stirred for 10 minutes to obtain a coating composition for
forming antireflective film.
[0110] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
EXAMPLE 14
[0111] In a container of 200 mL made of glass, 2 g of dispersion (solid content concentration:
20 mass%) of spherical solid fine particles (3), 2 g of dispersion (solid content
concentration: 15 mass%) of fibrous solid fine particles (1), 90 g of ethanol and
6 g of silicic acid oligomer solution (solid content concentration: 5 mass%) were
put, and the mixture was stirred for 10 minutes to obtain a coating composition for
forming antireflective film.
[0112] An antireflective film having a film thickness of 100 nm was formed in the same manner
as Example 1 except that the above coating composition was employed, and it was subjected
to various evaluations. Tables 1 and 2 show the results.
TABLE 2
|
External appearance |
Haze value (%) |
Minimum reflectivity (%) |
Before abrasion |
After abrasion |
△ reflectivity |
Ex. 1 |
○ |
0.1 |
0.9 |
1.2 |
0.3 |
Ex. 2 |
○ |
0.1 |
0.8 |
1.1 |
0.3 |
Ex. 3 |
○ |
0.1 |
0.7 |
1.1 |
0.4 |
Ex. 4 |
○ |
0.1 |
1.0 |
1.2 |
0.2 |
Ex. 5 |
○ |
0.1 |
0.7 |
0.8 |
0.1 |
Ex. 6 |
○ |
0.1 |
0.8 |
1.1 |
0.3 |
Ex. 7 |
○ |
0.1 |
0.8 |
1.0 |
0.2 |
Ex. 8 |
○ |
0.1 |
0.8 |
1.1 |
0.3 |
Ex. 9 |
○ |
0.1 |
0.8 |
1.2 |
0.4 |
Ex. 10 |
○ |
0.1 |
0.8 |
1.6 |
0.8 |
Ex. 11 |
○ |
0.1 |
1.2 |
2.0 |
0.8 |
Ex. 12 |
○ |
0.1 |
1.1 |
1.4 |
0.3 |
Ex. 13 |
○ |
0.1 |
0.6 |
1.3 |
0.7 |
Ex. 14 |
○ |
0.1 |
1.8 |
1.9 |
0.1 |
[0113] The antireflective films of Examples 1 to 9 each made from a coating composition
for forming antireflective film containing fibrous solid fine particles and hollow
fine particles, show sufficiently low reflectivity before abrasion and has high antireflective
effect. Further, these antireflective films show little change in reflectivity due
to abrasion, and accordingly, the films had high strength. Particularly, the antireflective
films of Examples 5 and 7 each made from a coating composition for forming antireflective
film containing fibrous hollow fine particles having an aspect ratio of 5.0 and fibrous
solid fine particles having an aspect ratio of 7.0, showed considerably low reflectivity
before abrasion, which were excellent in antireflective performance, which showed
extremely little change in reflectivity by abrasion, and they had high film strength.
Reflectivity before abrasion is preferably at most 1.0% in terms of minimum reflectivity
in a wavelength range of from 380 nm to 1,200 nm for practical use. Meanwhile, change
of minimum reflectivity between before and after abrasion is preferably at most 0.5%
for practical use, more preferably at most 0.3%.
[0114] The antireflective film of Example 10 made from a coating composition for forming
antireflective film containing no fibrous solid fine particles and containing hollow
fine particles, showed sufficiently low reflectivity before abrasion and had high
antireflective performance, but it showed significant change in reflectivity by abrasion,
and its film strength was insufficient.
[0115] The antireflective film of Example 11 made from a coating composition for forming
antireflective film containing spherical solid fine particles having small particle
size and containing hollow fine particles, showed high reflectivity before abrasion
and its antireflective performance was insufficient. Further, it showed significant
change in reflectivity by abrasion, and its film strength was insufficient.
[0116] The antireflective film of Example 12 made from a coating composition for forming
antireflective film containing spherical solid fine particles having large particle
size and containing hollow fine particles, showed high reflectivity before abrasion
and its antireflective performance was insufficient. On the other hand, it showed
little change in reflectivity by abrasion, and its film strength was high.
[0117] The antireflective film of Example 13 made from a coating composition for forming
antireflective film containing spherical hollow fine particles and fibrous hollow
fine particles showed sufficiently low reflectivity before abrasion, and its antireflective
performance was high, but it showed significant change in reflectivity by abrasion,
and its film strength was insufficient.
[0118] The antireflective film of Example 14 made from a coating composition for forming
antireflective film containing spherical solid fine particles and fibrous solid fine
particles showed high reflectivity before abrasion, and its antireflective performance
was insufficient. On the other hand, it showed little change in reflectivity by abrasion,
and its film strength was high.
[0119] The antireflective film of Example 15 made from a coating composition for forming
antireflective film containing spherical hollow fine particles and containing fibrous
solid fine particles having large particle size showed high reflectivity before abrasion,
and its antireflective performance was insufficient. On the other hand, since it contains
relatively large amount of fibrous solid fine particles, it showed little change in
reflectivity by abrasion, and its film strength was high.
INDUSTRIAL APPLICABILITY
[0120] An article on which the antireflective film made from the coating composition for
forming antireflective film of the present invention is formed, is useful for transparent
components for vehicles (headlight covers, side mirrors, front transparent substrates,
side transparent substrates, rear transparent substrates, etc.), opaque components
for vehicles (instrument panel surfaces, etc.), meters, architectural windows, show
windows, displays (notebook PCs, monitors, LCDs, PDPs, ELDs, CRTs, PDAs, etc.), LCD
color filters, substrates for touch panels, pickup lenses, optical lenses, glass lenses,
camera components, video components, cover substrates for CCDs, end faces of optical
fibers, projector components, copier machine components, transparent substrates for
solar cells, cell phone windows, backlight unit components (for example, light guide
plates, cold cathode ray tubes, etc.), LCD brightness-improving films for backlight
unit components (for example, prisms, half-transmission films, etc.), LCD brightness-improving
films, organic EL light-emitting element components, inorganic EL light-emitting element
components, fluorescent light-emitting element components, optical filters, end faces
of optical components, illumination lumps, covers for illumination devices, amplifying
laser light sources, antireflective films, polarizer films, films for agriculture
or the like.
[0121] The entire disclosure of Japanese Patent Application No.
2006-271015 filed on October 2, 2006 including specification, claims and summary is incorporated herein by reference in
its entirety.